smdiag: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/smdiag - from package: ax25-xtools

You may install the required package with command apt-get install {package}

Error in other languages:
smdiag: bevel nie gevind nie
smdiag: comandă negăsită
smdiag: comando não encontrado
smdiag: commande introuvable
smdiag: command not found
smdiag: käsku ei ole
smdiag: không tìm thấy lệnh
smdiag: komanda nerasta
smdiag: Kommando nicht gefunden.
smdiag: kommandot finns inte
smdiag: komut yok
smdiag: nie znaleziono polecenia
smdiag: níor aimsíodh an t-ordú
smdiag: no se encontró la orden
smdiag: no s'ha trobat l'ordre
smdiag: opdracht niet gevonden
smdiag: parancs nem található
smdiag: perintah tidak ditemukan
smdiag: príkaz nenájdený
smdiag: příkaz nenalezen
smdiag: команда не найдена
smdiag: командата не е открита
smdiag: 命令找不到
smdiag: コマンドが見つかりません